The dinosaurs disappeared by a massive meteor, that hit the earth. This made the volcanoes erupt, which threw ash everywhere. Including the sea, this killed the small fish, which took away the big fish's food; which kills them too. This is how the sea mammals died. Then the ash polluted the air; this affected the herbivores by getting in their throats then the carnivores had nothing to eat so everything was gone. Then humans began to evolve.